Power-steering control system

Abstract

In a power-steering control system installed in a vehicle, a state determiner determines whether an engine is in a state in which the engine is stopped. A steering-torque detector measures steering torque applied to a steering wheel by a driver of the vehicle. A controller holds the power steering motor in a ready state to generate the assist torque if it is determined that the engine is in the stop state and that the measured steering torque is equal to or higher than first threshold torque.

What is claimed is: 
     
         1 . A power-steering control system, installed in a vehicle, for controlling a power-steering motor that generates assist torque for assisting driver's turning effort of a steering wheel of the vehicle, the vehicle being designed to perform idle-reduction control to: stop an engine for generating drive power for the vehicle if a predetermined stop condition is met; and
 restart the stopped engine if a predetermined restart condition is met, the power-steering control system comprising:   a state determiner configured to determine whether the engine is in a state in which the engine is stopped;   a steering-torque detector configured to measure steering torque applied to the steering wheel by a driver of the vehicle; and   a controller configured to hold the power-steering motor in a ready state to generate the assist torque if it is determined that the engine is in the stop state and that the measured steering torque is equal to or higher than first threshold torque.   
     
     
         2 . The power-steering control system according to  claim 1 , wherein the engine restart condition includes a condition representing that the measured steering torque is equal to or higher than predetermined second threshold torque, and
 the controller is configured to:   deactivate the power steering motor upon a first determination that the engine is in the stop state and that the measured steering torque is lower than the first threshold torque; then   hold a deactivated state of the power-steering motor until the engine is restarted even upon a second determination that the engine is in the stop state and that the measured steering torque is equal to or higher than the first threshold torque.   
     
     
         3 . The power-steering control system according to  claim 2 , wherein the first threshold torque is identical to the second threshold torque.